I had to develop a PIC programmer for my company that was compact and
relies very little on controlling software.  What I came up with was to
use a pic that had the smarts to read in a hex file using a serial input
pin, decode the hex file on-the-fly inside the pic, and program the target
pic all at the same time.

I was able to do this all with a 16F84 and a transistor & fet for the 12V
control.  The 'F84 has a buffering uart in software to allow connection to
a PC (via a rs-232 driver like MAX232, of course).  Hardware flow control
is used.  From the pc, the hex file is simply copied to the serial port.
Led's on the programmer provide visual programming/success indications.

Just wondering if anything like this 'hex file decoder' has been done
before using the PIC?

        -Chris Cole
         cole@easyon.com